Teac C-1 User Manual

AMPLIFIER SECTION
When both REC and REC MUTE signals are low, the
conditions of the transistors are as follows:
ON ........ Q822, Q824, Q825, Q826
OFF ...... Q821, Q823
With Q824 turned on, the bias start signal is low and oscil-
lation is stopped. When Q826 is turned on, the collector
of Q826 generates about +1.5V and tums on Q308 and
Q315 thereby activating the muting circuit of the record-
ing amplifier.
When the REC signal goes high, Q821 tums on while Q822
turns off. With Q822 turned off, the charging current
flows in C801 via route (1). When about 7V is present at
point (A), Q823 turns on. Then, Q824 turns off, and the
collector goes high to start oscillation.
A delay of about 200 milliseconds elapses until an oscil-
lation start signal is delivered after a REC signal is re-
ceived. (A further 150 milliseconds are required to actually
start oscillation after the oscillation start signal is received
by the oscillator). When Q823 turns on, the charging
current flowing in C803 is stopped, and the charge in C803
is discharged via R838 and Q825. When the discharging
operation is completed, Q825 and Q826 turn off and then
Q308 and Q315 turn off, and the muting circuit of the
recording amplifier turns off.
About 100 milliseconds are required to release the muting
effect after Q823 turns on. These delay times are required
to prevent click noise from being recorded before starting
the program source recording.
When the REC MUTE signal goes high during the REC
mode, Q825 and Q826 tum on and thus Q308 and Q315
turn on. Then, the muting circuit of the recording amplifi-
er turns on. Since the bias oscillation is performed with
Q824 turned off at this time, no signal is recorded onthe
tape.
Ce] [R C MUTE STOP
RECORD B Ce
STOP REC PLAY REC MUTE REC PLAY STOP
REC ioe
HIGH
ss me
OFF
Q82! ON eee a4
asz2 oH
= 200mSec
OFF
Q823
ON
=
a
ae eae a
Q824
oN =100mSec =l00mSec
i a
OFF
Q825 ON
= + 15v ara
Q826 HIGH :
(COLLECTOR) Low Sev
MUTING OFF
(9308, 0315) ON
BIAS OSC
(ENVELOPE)
=(50mSec = lOm Sec
T-1319
Fig. 8 Record Control! Timing Chart
6-3 PMM DRIVE UNIT
This unit drives the peak level meter. The peak level meter
is preset to 10m sec for the attack time and 750m sec for
the recovery time.
27

Teac C-1 Specifications

General

Brand	Teac
Model	C-1
Category	Cassette Player
Language	English